14 CFR 21.120 : Aeronautics And Space (§ 1.1 To Parts 1311-1399) — (§ 1.1 To Parts 50-59) — Federal Aviation Administration, Department Of Transportation (§ 1.1 To Parts 50-59) — Aircraft (§ 21.1 To Parts 50-59) — Certification Procedures For Products And Articles (§ 21.1 To § 21.700) — Supplemental Type Certificates (§ 21.111 To § 21.120) — Responsibility of supplemental type certificate holders to provide written permission for alterations.
4 Aug 2016
A supplemental type certificate holder who allows a person to use the supplemental type certificate to alter an aircraft, aircraft engine, or propeller must provide that person with written permission acceptable to the FAA.